The present invention relates to a microwave electric power receiver for generating a DC power based on an electric power of a received microwave.
A technique for obtaining a DC power of a receiver from an electric power of a received microwave without arranging an operation power source in the receiver itself is disclosed in Japanese Patent Laid-Open No. 63-54023. The technique described in this patent will be briefly described below. A rectification diode is connected to one side of a rectangular microstrip resonator having a line length 1/2 of a wavelength .lambda. of a received microwave, and generates a DC power of a receiver from an electric power of a received microwave. In the technique described in the patent, one end of the diode is directly connected to the microstrip resonator. However, as is well known, in order to efficiently obtain a DC power, the microstrip resonator and the diode must be matched with each other.
Thus, an actual circuit arrangement employs a microstrip line for matching, as shown in FIG. 4. More specifically, one end of a matching microstrip line 2 is connected to one side of a rectangular microstrip resonator 1 having a .lambda./2 line length, and the other end of the line is connected to one end (e.g., cathode) of a rectification diode 3. The one end of the diode 3 is connected to an output terminal 5 through a choke coil 4 for removing a high frequency component. The other end (e.g., anode) of the diode 3 is grounded through another choke coil 6.
In this arrangement, the microstrip resonator 1 and the diode 3 are matched with each other by the microstrip line 2, and an electric power of a microwave received by the microstrip resonator 1 is relatively efficiently rectified by the diode 3. Thus, a DC power is generated at the output terminal 5.
As described above, in the technique for matching the microstrip resonator 1 and the diode 3 using the microstrip line 2, an electric power of a microwave transmitted to the diode 3 is efficiently rectified by the diode 3. However, the electric power is attenuated more or less by a transmission loss while it is transmitted from the microstrip resonator 1 to the diode 3. Therefore, a DC power cannot be obtained by a sufficient electric power due to this attenuation.